The invention described herein relates to the field of detecting perchlorate. Perchlorate has been used as the oxidizer component and primary ingredient in solid propellant for rockets and missiles. Recently it was shown that perchlorate is present in several fertilizers and fertilizer components at levels up to 0.84 wt %, suggesting that fertilizers could be a source for perchlorate accumulation in the food chain. Perchlorate is exceedingly mobile in aqueous systems and can persist for many decades under typical ground- and surface-water conditions. It has been found in groundwater, drinking water, and soils, mainly in the southwestern United States, at levels ranging from 8 to 3700 ppb. Perchlorate affects the thyroid gland by blocking iodine uptake resulting in lower thyroid hormone levels. There is a need for an improved perchlorate detector.